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Macrophage expression of class II major histocompatibility complex gene products in Paracoccidioides
A L Bocca1, M F Silva, C L Silva
1Department of Cell Biology, Biology Institute, Faculty of Health Sciences, University of Brasília, Brasília DF, Brazil.
Abstract:
C57B1/6 isogenic mice infected with Paracoccidioides brasiliensis strains showed a disruption in the expression of Ia antigen. Expression slowly decreased during the course of the infection with a slight variation dependent on the route of inoculation and the fungal strain used, but production of interferon-gamma and tumor necrosis factor-alpha were observed. Suppression of Ia antigen expression and depression of the immunoproliferative responses of spleen cells were strongly correlated with nitric oxide levels. These parameters were inhibited when the animals were treated with nitro-L-arginine, which resulted in inhibition the activation of nitric oxide (NO) production. Analysis of the data showed that changes in the expression of the Ia antigen occur in P. brasiliensis infection and are strongly correlated with NO levels. These phenomena may be interrelated and reflect macrophage activation that contributes to the control of the disease and to the immunosuppression observed during the course of the infection.
Insights
Paracoccidioides brasiliensis infection in mice suppresses Ia antigen expression, correlating with nitric oxide (NO) levels. This suggests NO-mediated macrophage activation impacts disease control and immunosuppression.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Paracoccidioides brasiliensis is a fungus causing paracoccidioidomycosis.
- Immune responses, including antigen presentation and cytokine production, are crucial for controlling fungal infections.
Purpose of the Study:
- To investigate the modulation of Ia antigen expression during P. brasiliensis infection in mice.
- To explore the correlation between Ia antigen expression, immune cell responses, and nitric oxide (NO) production.
Main Methods:
- C57B1/6 mice were infected with P. brasiliensis.
- Flow cytometry was used to assess Ia antigen expression.
- Interferon-gamma and tumor necrosis factor-alpha production were measured.
- Nitric oxide (NO) levels were analyzed.
- Mice were treated with nitro-L-arginine to inhibit NO production.
Main Results:
- P. brasiliensis infection led to decreased Ia antigen expression in mice.
- Suppression of Ia antigen correlated with elevated nitric oxide (NO) levels.
- Immunoproliferative responses of spleen cells were depressed and linked to NO levels.
- Inhibition of NO production by nitro-L-arginine reversed these effects.
Conclusions:
- Changes in Ia antigen expression during P. brasiliensis infection are strongly associated with nitric oxide (NO) levels.
- NO-mediated macrophage activation appears to play a dual role in P. brasiliensis infection, contributing to both disease control and immunosuppression.